/////////////////////////////////////////////////////////////////////////////
// Original code from libhdfs3. Copyright (c) 2013 - 2014, Pivotal Inc.
// All rights reserved. Author: Zhanwei Wang
/////////////////////////////////////////////////////////////////////////////
//  Modifications by Kumo Inc.
// Copyright (C) Kumo inc. and its affiliates.
// Author: Jeff.li lijippy@163.com
// All rights reserved.
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published
// by the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.
//



#pragma once

#include <string>
#include <vector>
#include <functional>

namespace Hdfs {
    namespace Internal {
        /**
         * A hash function object used to hash a boolean value.
         */
        extern std::hash<bool> BoolHasher;

        /**
         * A hash function object used to hash an int value.
         */
        extern std::hash<int> Int32Hasher;

        /**
         * A hash function object used to hash an 64 bit int value.
         */
        extern std::hash<int64_t> Int64Hasher;

        /**
         * A hash function object used to hash a size_t value.
         */
        extern std::hash<size_t> SizeHasher;

        /**
         * A hash function object used to hash a std::string object.
         */
        extern std::hash<std::string> StringHasher;
    }
}

#define HDFS_HASH_DEFINE(TYPE) \
    namespace std{ \
    template<> \
    struct hash<TYPE> { \
        std::size_t operator()(const TYPE & key) const { \
            return key.hash_value(); \
        } \
    }; \
    }

namespace Hdfs {
    namespace Internal {
        /**
         * A hash function used to hash a vector of size_t values.
         * @param vec The vector's reference which items are to be hashed.
         * @param size The size of vec.
         * @return The hash value.
         * @throw nothrow
         */
        static inline size_t CombineHasher(const size_t *vec, size_t size) {
            size_t value = 0;

            for (size_t i = 0; i < size; ++i) {
                value ^= SizeHasher(vec[i]) << 1;
            }

            return value;
        }
    }
}
